LXR linux/arch/mips/sgi-ip22/ip22-nvram.c

   1/*
   2 * ip22-nvram.c: NVRAM and serial EEPROM handling.
   3 *
   4 * Copyright (C) 2003 Ladislav Michl (ladis@linux-mips.org)
   5 */
   6#include <linux/module.h>
   7
   8#include <asm/sgi/hpc3.h>
   9#include <asm/sgi/ip22.h>
  10
  11/* Control opcode for serial eeprom  */
  12#define EEPROM_READ     0xc000  /* serial memory read */
  13#define EEPROM_WEN      0x9800  /* write enable before prog modes */
  14#define EEPROM_WRITE    0xa000  /* serial memory write */
  15#define EEPROM_WRALL    0x8800  /* write all registers */
  16#define EEPROM_WDS      0x8000  /* disable all programming */
  17#define EEPROM_PRREAD   0xc000  /* read protect register */
  18#define EEPROM_PREN     0x9800  /* enable protect register mode */
  19#define EEPROM_PRCLEAR  0xffff  /* clear protect register */
  20#define EEPROM_PRWRITE  0xa000  /* write protect register */
  21#define EEPROM_PRDS     0x8000  /* disable protect register, forever */
  22
  23#define EEPROM_EPROT    0x01    /* Protect register enable */
  24#define EEPROM_CSEL     0x02    /* Chip select */
  25#define EEPROM_ECLK     0x04    /* EEPROM clock */
  26#define EEPROM_DATO     0x08    /* Data out */
  27#define EEPROM_DATI     0x10    /* Data in */
  28
  29/* We need to use these functions early... */
  30#define delay() ({                                              \
  31        int x;                                                  \
  32        for (x=0; x<100000; x++) __asm__ __volatile__(""); })
  33
  34#define eeprom_cs_on(ptr) ({    \
  35        __raw_writel(__raw_readl(ptr) & ~EEPROM_DATO, ptr);     \
  36        __raw_writel(__raw_readl(ptr) & ~EEPROM_ECLK, ptr);     \
  37        __raw_writel(__raw_readl(ptr) & ~EEPROM_EPROT, ptr);    \
  38        delay();                                                \
  39        __raw_writel(__raw_readl(ptr) | EEPROM_CSEL, ptr);      \
  40        __raw_writel(__raw_readl(ptr) | EEPROM_ECLK, ptr); })
  41
  42
  43#define eeprom_cs_off(ptr) ({   \
  44        __raw_writel(__raw_readl(ptr) & ~EEPROM_ECLK, ptr);     \
  45        __raw_writel(__raw_readl(ptr) & ~EEPROM_CSEL, ptr);     \
  46        __raw_writel(__raw_readl(ptr) | EEPROM_EPROT, ptr);     \
  47        __raw_writel(__raw_readl(ptr) | EEPROM_ECLK, ptr); })
  48
  49#define BITS_IN_COMMAND 11
  50/*
  51 * clock in the nvram command and the register number. For the
  52 * national semiconductor nv ram chip the op code is 3 bits and
  53 * the address is 6/8 bits.
  54 */
  55static inline void eeprom_cmd(unsigned int *ctrl, unsigned cmd, unsigned reg)
  56{
  57        unsigned short ser_cmd;
  58        int i;
  59
  60        ser_cmd = cmd | (reg << (16 - BITS_IN_COMMAND));
  61        for (i = 0; i < BITS_IN_COMMAND; i++) {
  62                if (ser_cmd & (1<<15))  /* if high order bit set */
  63                        __raw_writel(__raw_readl(ctrl) | EEPROM_DATO, ctrl);
  64                else
  65                        __raw_writel(__raw_readl(ctrl) & ~EEPROM_DATO, ctrl);
  66                __raw_writel(__raw_readl(ctrl) & ~EEPROM_ECLK, ctrl);
  67                delay();
  68                __raw_writel(__raw_readl(ctrl) | EEPROM_ECLK, ctrl);
  69                delay();
  70                ser_cmd <<= 1;
  71        }
  72        /* see data sheet timing diagram */
  73        __raw_writel(__raw_readl(ctrl) & ~EEPROM_DATO, ctrl);
  74}
  75
  76unsigned short ip22_eeprom_read(unsigned int *ctrl, int reg)
  77{
  78        unsigned short res = 0;
  79        int i;
  80
  81        __raw_writel(__raw_readl(ctrl) & ~EEPROM_EPROT, ctrl);
  82        eeprom_cs_on(ctrl);
  83        eeprom_cmd(ctrl, EEPROM_READ, reg);
  84
  85        /* clock the data ouf of serial mem */
  86        for (i = 0; i < 16; i++) {
  87                __raw_writel(__raw_readl(ctrl) & ~EEPROM_ECLK, ctrl);
  88                delay();
  89                __raw_writel(__raw_readl(ctrl) | EEPROM_ECLK, ctrl);
  90                delay();
  91                res <<= 1;
  92                if (__raw_readl(ctrl) & EEPROM_DATI)
  93                        res |= 1;
  94        }
  95
  96        eeprom_cs_off(ctrl);
  97
  98        return res;
  99}
 100
 101EXPORT_SYMBOL(ip22_eeprom_read);
 102
 103/*
 104 * Read specified register from main NVRAM
 105 */
 106unsigned short ip22_nvram_read(int reg)
 107{
 108        if (ip22_is_fullhouse())
 109                /* IP22 (Indigo2 aka FullHouse) stores env variables into
 110                 * 93CS56 Microwire Bus EEPROM 2048 Bit (128x16) */
 111                return ip22_eeprom_read(&hpc3c0->eeprom, reg);
 112        else {
 113                unsigned short tmp;
 114                /* IP24 (Indy aka Guiness) uses DS1386 8K version */
 115                reg <<= 1;
 116                tmp = hpc3c0->bbram[reg++] & 0xff;
 117                return (tmp << 8) | (hpc3c0->bbram[reg] & 0xff);
 118        }
 119}
 120
 121EXPORT_SYMBOL(ip22_nvram_read);
 122